This invention relates generally to mechanical equipment shaft sealing devices and more particularly concerns a shaft seal mechanism which seals effectively when a shaft is at rest, and which changes configurations so as to seal effectively but without friction when the shaft is rotating at an operating speed.
Auxiliary mechanical equipment shaft seals, sometimes called bearing isolators or sealing rings, have become increasingly important to modern mechanical equipment, especially for equipment called upon to operate in hostile applications. For example, mechanical power transmission units used in rock quarries are often subjected to highly abrasive dust particles. Normal elastomeric lip or O-ring shaft seals can quickly wear out and fail in environments such as these. Dust and exterior contaminants cannot be excluded from the interior of the transmission housing by a failed standard sealing device. Nor can oil or other fluids be prevented from leaking out of the transmission devices past a ruined O-ring or a worn lip seal.
To prevent the ingress of corruption and the egress of lubricating fluids, a number of auxiliary or improved primary sealing arrangements and devices have been provided. Some of these sealing devices provide a physical engagement of the shaft and a wiping action while the shaft operates. Other devices provide an interengagement and wiping action between seal parts. But in both such arrangements, the inevitable friction causes inevitable part wear. Moreover, that friction can significantly degrade equipment performance in some situations.
Some of these commercially successful seal devices do not require any actual physical interengagement of the sealing member parts. Among such devices which have met with considerable commercial acceptance are those disclosed in Orlowski U.S. Pat. Nos. 4,706,968; 4,466,620; 4,175,752; 4,114,902; and 4,022,479.
It is the general object of the present invention to provide a seal for use with machinery having a housing through which a rotatable shaft protrudes, and which provides effective part-to-part contact static sealing action when the shaft is stationary and which provides effective non-contact dynamic sealing action when the shaft is rotating.
It is another object to provide a machinery seal of the type described in which a seal member engages both a seal stator and a seal rotor when the shaft is at rest, but in which the sealing member disengages from the stator when the shaft rotates at a normal operating speed.
Yet another object to provide a seal of the type described which is relatively inexpensive to manufacture.
Still another object is to provide a seal of the type described which will provide a long, trouble-free service life.
To accomplish these objectives, an isolator mechanism is provided for use with a machinery housing and a rotatable shaft protruding through the housing. The isolator mechanism comprises a stator ring affixed to the housing and a rotor ring which is attached to the shaft. The stator and rotor are so shaped that the stator has a male cylindrical surface, and the rotor has a female cylindrical surface located radially outwardly of the stator male surface. A deformable annular seal member is mounted on the rotor female surface and engages the stator male surface when the rotor and seal member are at rest. However, the seal member is deformed by centrifugal force into a configuration out of engagement with the stator when the rotor and seal member are moving at operating speeds.
Other objects, advantages and embodiments of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.